Semiconductor devices are used in a variety of electronic and other applications. Semiconductor devices comprise, among other things, integrated circuits or discrete devices that are formed on semiconductor wafers by depositing one or more types of thin films of material over the semiconductor wafers, and patterning the thin films of material to form the integrated circuits.
Semiconductor devices are fabricated on semiconductor wafers, which are usually bulk semiconductor wafer. Bulk semiconductor wafers are formed using a Czochralski, float zone, or other processes. Semiconductor on insulator (SOI) substrate is another type of substrate that is gaining popularity. These substrates are being increasingly favored for the possibility of improved isolation of the device regions and result in devices with reduced leakage currents and parasitic effects. However, manufacturing SOI wafers requires additional processing of the bulk wafers. For example, SOI wafers are formed using an oxygen implantation such as in a SIMOX process, or using wafer bonding processes such as Smart Cut process in which two substrates are bonded together. Consequently, the manufacturing costs of producing SOI wafers are much higher than conventional bulk wafers. Additionally, due to the difficulty of the fabrication process, the supply of these wafers is limited. Further, the bottom layer of the SOI wafer cannot be contacted electrically using conventional contact forming processes.